Silencer



Sept. 28 1926.

H. P. MAXIM SILENCER f mv f.

BY .f

. AT'ORNEYS Filed Oct." 29, 1924 5' thereof opening into each -Patente-cl Sept. 28, 1926.

UNITED lSTATES PATENT OFFICE.

v HIRAM PERCY MAXIM, OF HARTFORD, CONNECTICUT, ASSIGNOR T0 MAXIM SILENCER COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OF CONNECTICUT.

SILENCER. i

g Application -filed. October 29, 1924.\ Serial No. 746,614.

This invention relates to silencers such as are used for silencing the exhaust noises of internal combustion engines and is especially designed to be used in silencing the exhaust noises of small engines of the outboard type having one or two cylinders.

One object of the invention is to provide a compact and light silencer for an engine of the labove type which eifectually silences the exhaust with a minimum of back pressure thereby rendering a cut out necessary.

Another object is to provide a silencer wherein thek various improved features of construction and design contribute to the eiiiciency and durability of same and to the production of an efficient and reliable silencer at low manufacturing cost.

To the accomplishment of the above and further objects as will hereinafter appear,

the invention consists in the features of construction and in the combination and arrangement of parts which will be first described and then particularly pointed out'in the claims.

The invention will be explained in connection with the accompanying'drawings in which: i i l Fig. 1 is a side view partly in section of a silencer designed for a two cylinder engine; l

Fig. 2 is a vertical section taken on the line 2-2 of Fig. 1; i f

Fig. 3 is a side view of the outer shell of the silencer;

Fig. 4 is a broken the inner shells; and i Fig. 5 is a longitudinal sectionalized view of a modification adapted for use with a single cylinder engine.

Referring to the drawings,-the improved form of silencer shown in Fig. 1 is designed for use a two cylinder out board motor of side View of one of the usual type having its cylinders diametrically opposed and with simultaneous exhaust. This form consists of the outer cylindrical shell 1, preferably constructed of sheet metal seamed longitudinally at 2, as shown in Fig. 3. The ends of the shell are closed by removable annular plates 3, 3, each of which is provided with a circumferential flange 4, fitting tightly over the ends of the shell 1. Each end plate 3 also has a hollow axial protuberance 5 to provide a small axial chamber 6 in the inner wall Y end of the shell 1 and integral with said end plate is an arm 8 adapted for use as a supporting arm in attaching said silencer to the engine (not.

shown). The arm 8 may also be hollow to provide a passageway 7 leading from the exhaust port of the engine to the inlet side of said silencer.

within aie Shen 1 is a silencing device 9 preferably constructed of two annular scroll members or units 10, 10, each formed to provide a Continous winding or spiral channel 11, 11, united as one passageway leading from the axis to the periphery thereof. To this end, each of the members 10, 10 comprises a flat annular plate 12 with a central aperture 15 and what is in effect a spiral rib 13 which projects at right angles to the plate 12 and which forms between its convolutions the winding lor spiral channel 11 for the exhaust gases. In

practice, it is preferred to make the ribS 13 not as true spirals but concentric circular segments for somewhat more than three quarters of a circle and to connect the corresponding ends of each concentric portion with the opposed ends of the ribs of the next smaller diameter, as clearly shown in Fig. 2. The outer convolution or concentric segmental rib is at the periphery of the plate, and is adapted to be slightly smaller in diameter than the inside diameter of the shell 1. These two scroll members 10, 10`

are identical in construction and are assembled within the shell 1 with the free edges of their respective spiral ribs 13 in abutting relation during the entire length thereof, and with these edges meeting at a point approximately midway between the ends of the shell 1. Due to the slightly smaller diameter of the outer convolution of these members, they are easily assembled within the shell, but fit snugly therewithin and are removable for cleaning. Other forms of removable silencing units composed of annular plates with axially projectifi'g ribs to provide a tortuous passageway extending radially outward from the central opening may also be used in a similar manner to that shown.

It will be seen that by thus assembling the two scroll members 10, 10 within the shell an expansion chamber 14 is formed at each end thereof, and these chambers 14 are connected by an axial passageway formed by the centrally located apertures 15 in the members. It is also apparent that the two spiral channels 11, 11 form ya single continuous closed spiral passageway which leads from the axis'of the'shell to the pe riphery thereof; the inner and outer ends of the spiral ribs forming respectively the inlet 16 and the outlet 17 to sai'd passageways. That portion of the shell 1- at the outer end of the spiral passageway which registers therewith is cut away forming a lateral port 18 inthe shell 1, whereby the exhaust gases are discharged into the atmos phere. v i

In order to strengthen the assembly of the various parts of the device and to assist in holding the scroll members 10, 10 in place, I provide two inner cylindrical shells 19, 19

.which are slightly 'smaller in diameter than the outer shell 1, and are preferably constructed of sheet metal seamed at 20, as shown in Fig. 4; These inner shells 19, 19 fit closely within the outer shell 1 and extend from opposite ends of the scroll members 10, 10 to the inner walls of the en'd plates 3, 3. A tie-bolt 21, provided at either end with nuts 22, 22, extends through shell 1 and the end plates 3, 3, thereby firmly holding the parts together, as clearly shown in Fig. 1.

In use with an engine of the type having` two opposed cylinders with simultaneous exhaust, the exhaust gases and sound waves from each cylinder pass into the expansion` chambers 14, 14 at either end of the silencer simultaneously and then into the axial passageway 15 connecting the two chambers 14, 14 where the gases and sound waves of one cylinder oppose those of the other an'd are thereby constrained to pass through` the spiral passagewayl 11 and 4out through the lateral port 18 into the atmosphere. During the passage of the gases and sound waves end plate 3 in this manner, the sound waves are largely trapped by repeated reflections against the Walls ,of the chambers 14 and of the spiral passageway 11 whereby the remnants of sound Waves fLnally emerging from the lateral port 18 are substantially noiseless.

e gases on the other hand flow easilyin a `spiral course toward the discharge port 18 and are not substantially retarded in their How, thereby avoiding excessive back pressure on the engine.

I n Fig. 5, I have shown the adaptation to a single cylinder engine of a silencer of the above type, and will now describe briefly the construction of the same.

Referring to Fig. 5, this form consists of the outer cylindrical shell 1 having its ends closed by the end plates 3 and 3". The has a hollow protuberance 5 to provide a `small axial chamber 6 in the inner wall thereof opening into one end of the shell 1, but thel other end plate 3" is preferably constructed without any axial lthe'hollow supporting arm 8 other end plate 3"- chamber. Integral with the end plate 3 is having the therein for receiving the exsingle cylinder engine. The is lalso provided with its integral supporting arm 8, but is without the hollow passageways 7 or chamber 5.

Within the shell 1 is a single scroll member 10 constructed in all respects similar to one of the members. 10 of the rst described type of silencer. This member 10 is assembled within the shell 1 with the free edges of its spiral rib in abutting relation with the inner wall of the end plate 3 thus providing an expansion chamber 14' at inlet end of the silencer. There is also provided an inner cylindrical shell 19 for the same purposes and of the same construction as the shell 19, 19 of the first described type of silencer. A tie-bolt 21l provided with nuts 22', 22 extends through the shell and the end plates 3', 3 and holds the parts firmly together. y

In the use of this type of silencer with a single cylinder engine, the gases act similar as in the first described type. andare exhausted through the lateral port 18 formed in the shell 1 'A It will be thus observed that an improved silencer for a two cylinder engine having simultaneous impulses or for a single cylinder engine has been constructed in which the various parts are compactly arranged and firmly secured together by a single bolt. The improved silencer may be of very light construction, is easily and quickly lassembled and provides an extremely efiicient and durable muier for engines of the above types. A further advantage lies in the fact that the parts of the silencer are removable and may be easily disassembled for cleaning.

What I claim-is:

l. A silencer for internal combustion engines and the like comprising, acylindrical shell, end members for closing the ends of said shell, each of said end members having an inlet for the exhaust gases, a pair of scroll members fitting within said shell and each comprising a centrally apertured base with a spiral rib projecting therefrom, said scroll members beingassembled within said shell in opposed relation with the free edges of their respective ribs abutting to provide a closed spiral passageway extending from the axis of said shell to the periphery thereof, means for spacing said abutting scroll members from each end of said shell to provide an expansioh chamber /at each side of said'annular member, and a lateral exhaust port in the side wall of said shell intermediate the ends thereof.

2. A silencer for internal combustion engines and the like comprising, an outer cylindrical shell, end members for closing the endslof said shell, each of said end members passageway 7 haust of the having an inlet for the exhaust gases, a pair of scroll members fitting within said shell and each comprising a centrally apertured base with a spiral rib projecting therefrom, said scroll members being assembled within said shell lin opposed relation with the free edges of their respective ribs abutting to rovide a closed spiral passageway extending from the axis of said shell to the periphery thereof, inner spacing shells between said scroll members and the end members to provide an expansion chamber at each side of said annular "members, a lateral exhaust port in the side wall of said outer shell intermediate 'the ends thereof and a single tie bolt for holding the various parts in as sembled position..y Y

3. A silencer for an internal combustion engine and the like, comprising a cylindrical shell, end members for closingthe ends of said shell, one of said end membershaving an inlet for the exhaust gases, a scroll mem-- ber fitting within said shell comprising a centrally apertured base with a spiral rib projecting therefrom to form a closed spiral passageway from the axis to the peri-pheryof said shell, said scroll member being spaced from the inlet end member to provide an Aexpansion chamber for said gases, and a lateral outlet for said gases in the side of -said cylindrical shell.

4. A silencer for an internal combustion engine and the like, comprising a cylindrical shell, end members for closing the ends of said shell, one of-said end members having an inlet for the exhaust gases, a scroll mem-l ber ittingwithin said shell comprising a centrally apertured base with `a spiral rib projecting therefrom to form a closed spiral passageway from the axis to the periphery of said shell, a lateral opening for the said gases n the side of said cylindrical shell, means for spacing the base of said scroll member from the inlet en member to pro- Vide an expansion chamber for the exhaust gases and a single tie bolt for holding said parts in assembled relation.

In testimony whereof I have affixed my signature.

HIRAM PERCY MAXIM.

v Certificate of1 Correction. It isl hereby certified that in Letters Pate-nt No. 1,601,136, grantedA September 28,

1926, upon theiapplication of Hiram Percy Maxim,

errors ap ear in the printed specification aim l, and page 3, lline 13, claim vimprovement in Silence'rs, correction as follows: Igage 2, line 124, c word annular readscf'oll; page 3, line insert therword opening,- corrections therein -that the same may Oiiice.

Signed [SEAL] and thatthe said Letters conform to the record of Hartford, Connecticut, fonan requiring 2, for the 30, claim 3, after the Word outlet Patentlshould be read with these of the case in the Patent and sealedthis 19th day of October, A, D. 1926. g

c 'WM. A. KINNAN, Acting 'ommz'ssfifmer of P atente. 

